The present invention relates generally to a box spring assembly using formed wire springs to support a mattress, and more particularly to an improved box spring assembly of low profile construction having an improved feeling of firmness. Formed wire springs are often used in box spring assemblies as illustrated in U.S. Pat. Nos. 3,286,281; 3,487,480; 3,574,241; 3,665,529; and 3,852,838, all of which are assigned to the assignee of the present application. Although box spring assemblies using formed wire springs such as those disclosed in the above applications are generally understood to offer a firm foundation, greater and greater firmness is becoming associated in the public mind with quality bedding. The increased demand for firm support bedding has arisen because of the widespread belief that beds which offer firm support are advantageous from the standpoints of being more comfortable and physically beneficial to the user. The desired firmness can be achieved in some instances by increasing the size of the wires which constitute the box spring assembly, but that necessitates an increase in the weight of the box spring assembly and an increase in the cost of its manufacture. There is a need, therefore, for a box spring assembly having formed wire springs which provide a firm support to the user and which can be manufactured from a minimum amount of material. It is also desirable to construct these formed wire springs with a low profile, namely, relatively short vertical height, so as to facilitate the construction of box spring assemblies having a variety of heights without changing the construction of the formed wire spring.
It is an object of the present invention, therefore, to provide an improved low profile formed wire box spring assembly that offers increased resistance to downwardly directed loads.